Modify your apache /etc/apache2/ports.conf file to listen for a different port than 80. Because port 80 is already used by Nginx.

[code]
# If you just change the port or add more ports here, you will likely also
# have to change the VirtualHost statement in
# /etc/apache2/sites-enabled/000-default.conf

Listen 81

<IfModule ssl_module>
Listen 443
</IfModule>

<IfModule mod_gnutls.c>
Listen 443
</IfModule>
[/code]

If you plan to use Apache only for svn http access then you can modify /etc/apache2/sites-available/000-default.conf directly, otherwise you shoul create a virtual host file in /etc/apache2/sites-available and enable it via a2ensite.